syscall: drop compatibility for FreeBSD < 10.0

Change-Id: Idd8cee84215e61817a86915160c91242670798af
Reviewed-on: https://go-review.googlesource.com/c/go/+/431663


Reviewed-by: Yuval Pavel Zholkover <paulzhol@gmail.com>
Reviewed-by: Dmitri Goutnik <dgoutnik@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>

src/syscall/route_freebsd_32bit.go

@@ -22,12 +22,9 @@ func (any *anyMessage) parseInterfaceMessage(b []byte) *InterfaceMessage {
 	// FreeBSD 10 and beyond have a restructured mbuf
 	// packet header view.
 	// See https://svnweb.freebsd.org/base?view=revision&revision=254804.
-	if supportsABI(1000000) {
-		m := (*ifMsghdr)(unsafe.Pointer(any))
-		p.Header.Data.Hwassist = uint32(m.Data.Hwassist)
-		p.Header.Data.Epoch = m.Data.Epoch
-		p.Header.Data.Lastchange = m.Data.Lastchange
-		return &InterfaceMessage{Header: p.Header, Data: b[int(unsafe.Offsetof(p.Header.Data))+int(p.Header.Data.Datalen) : any.Msglen]}
-	}
+	m := (*ifMsghdr)(unsafe.Pointer(any))
+	p.Header.Data.Hwassist = uint32(m.Data.Hwassist)
+	p.Header.Data.Epoch = m.Data.Epoch
+	p.Header.Data.Lastchange = m.Data.Lastchange
 	return &InterfaceMessage{Header: p.Header, Data: b[int(unsafe.Offsetof(p.Header.Data))+int(p.Header.Data.Datalen) : any.Msglen]}
 }

src/syscall/syscall_freebsd.go

@@ -12,27 +12,13 @@
 
 package syscall
 
-import (
-	"sync"
-	"unsafe"
-)
+import "unsafe"
 
 func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
 func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 
-// See https://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/versions.html.
-var (
-	osreldateOnce sync.Once
-	osreldate     uint32
-)
-
-func supportsABI(ver uint32) bool {
-	osreldateOnce.Do(func() { osreldate, _ = SysctlUint32("kern.osreldate") })
-	return osreldate >= ver
-}
-
 type SockaddrDatalink struct {
 	Len    uint8
 	Family uint8